Final answer:
A non-coding RNA is a type of RNA that does not get translated into a polypeptide; instead, it has roles such as in the structural components of the ribosome (rRNA) or in carrying amino acids during protein synthesis (tRNA).
Step-by-step explanation:
An RNA that does not encode a polypeptide is known as a non-coding RNA. These RNAs, such as rRNA (ribosomal RNA) and tRNA (transfer RNA), have structural and regulatory roles within the cell but are not translated into proteins. rRNA is a major component of ribosomes, playing both structural and catalytic roles, while tRNA carries amino acids to the ribosome during protein synthesis.
mRNA (messenger RNA) undergoes processing to remove non-coding sequences called introns, leaving only the coding sequences, or exons, which are translated into proteins. Unlike mRNA, non-coding RNAs such as rRNA and tRNA do not undergo translation but are still essential for the process of protein synthesis.